# Example 4

- Author:
- Walch Education

A car’s total stopping distance in feet depends on many factors, but can be approximated by the expression , for which

*x*is the speed of the car in miles per hour. Is this expression quadratic? What effect does doubling the car’s speed from 10 mph to 20 mph have on the total stopping distance?- Determine whether the expression is quadratic.
- Determine the stopping distance of a car traveling 10 mph.
- Determine the stopping distance of a car traveling 20 mph.
- Compare the stopping distances for a car traveling 10 mph and a car traveling 20 mph.